//
//  NSDate+EUHelper.m
//  CalendarDemo
//
//  Created by liubiqu on 12-4-18.
//  Copyright (c) 2012年 com.eu. All rights reserved.
//

#import "NSDate+EUHelper.h"

@implementation NSDate (EUHelper)

/*
 * This guy can be a little unreliable and produce unexpected results,
 * you're better off using daysAgoAgainstMidnight
 */
//获取年月日如:19871127.
- (NSString *)getFormatYearMonthDay {
    NSString *string = [NSString stringWithFormat:@"%d%02d%02d", [self getYear], [self getMonth], [self getDay]];
    return string;
}

//返回当前月一共有几周(可能为4,5,6)
- (int)getWeekNumOfMonth {
    return [[self endOfMonth] getWeekOfYear] - [[self beginningOfMonth] getWeekOfYear] + 1;
}
//该日期是该年的第几周
- (int)getWeekOfYear {
    int i;
    int year = [self getYear];
    NSDate *date = [self endOfWeek];
    for (i = 1;[[date dateAfterDay:-7 * i] getYear] == year; i++) {
    }
    return i;
}
//返回day天后的日期(若day为负数,则为|day|天前的日期)
- (NSDate *)dateAfterDay:(int)day {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    // Get the weekday component of the current date
    // NSDateComponents *weekdayComponents = [calendar components:NSCalendarUnitWeekday fromDate:self];
    NSDateComponents *componentsToAdd = [[NSDateComponents alloc] init];
    // to get the end of week for a particular date, add (7 - weekday) days
    [componentsToAdd setDay:day];
    NSDate *dateAfterDay = [calendar dateByAddingComponents:componentsToAdd toDate:self options:0];
    return dateAfterDay;
}
// month个月后的日期
- (NSDate *)dateafterMonth:(int)month {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *componentsToAdd = [[NSDateComponents alloc] init];
    [componentsToAdd setMonth:month];
    NSDate *dateAfterMonth = [calendar dateByAddingComponents:componentsToAdd toDate:self options:0];

    return dateAfterMonth;
}
//获取日
- (int)getDay {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *dayComponents = [calendar components:(NSCalendarUnitDay) fromDate:self];
    return (int)[dayComponents day];
}
//获取月
- (int)getMonth {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *dayComponents = [calendar components:(NSCalendarUnitMonth) fromDate:self];
    return (int)[dayComponents month];
}
//获取年
- (int)getYear {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *dayComponents = [calendar components:(NSCalendarUnitYear) fromDate:self];
    return (int)[dayComponents year];
}
//获取小时
- (int)getHour {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSUInteger unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute;
    NSDateComponents *components = [calendar components:unitFlags fromDate:self];
    NSInteger hour = [components hour];
    return (int)hour;
}
//获取分钟
- (int)getMinute {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSUInteger unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute;
    NSDateComponents *components = [calendar components:unitFlags fromDate:self];
    NSInteger minute = [components minute];
    return (int)minute;
}
- (int)getHour:(NSDate *)date {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSUInteger unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute;
    NSDateComponents *components = [calendar components:unitFlags fromDate:date];
    NSInteger hour = [components hour];
    return (int)hour;
}
- (int)getMinute:(NSDate *)date {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSUInteger unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute;
    NSDateComponents *components = [calendar components:unitFlags fromDate:date];
    NSInteger minute = [components minute];
    return (int)minute;
}
//在当前日期前几天
- (int)daysAgo {
    NSDateFormatter *mdf = [[NSDateFormatter alloc] init];
    [mdf setDateFormat:@"yyyy-MM-dd"];
    NSDate *midnight = [mdf dateFromString:[mdf stringFromDate:self]];
    NSString *strDate = [NSString stringWithFormat:@"%@ 23:59:59", [mdf stringFromDate:self]];
    NSDate *midnight24 = [NSDate dateFromString:strDate withFormat:@"yyyy-MM-dd HH:mm:ss"];
    return (int)[[self compare:[NSDate date]] == NSOrderedAscending ? midnight : midnight24 timeIntervalSinceNow] / (60 * 60 * 24) * -1;
    //        NSCalendar *calendar = [NSCalendar currentCalendar];
    //        unsigned int unitFlags = NSCalendarUnitDay;
    //        NSDateComponents *components = [calendar components:unitFlags
    //                                                   fromDate:self
    //                                                     toDate:[NSDate date]
    //                                                    options:0];
    //        return [components day];
}

//午夜时间距今几天
- (int)daysAgoAgainstMidnight {
    // get a midnight version of ourself:
    NSDateFormatter *mdf = [[NSDateFormatter alloc] init];
    [mdf setDateFormat:@"yyyy-MM-dd"];
    NSDate *midnight = [mdf dateFromString:[mdf stringFromDate:self]];
    return (int)[midnight timeIntervalSinceNow] / (60 * 60 * 24) * -1;
}

- (NSString *)stringDaysAgo {
    return [self stringDaysAgoAgainstMidnight:NO];
}

- (NSString *)stringDaysAgoAgainstMidnight:(BOOL)flag {
    int daysAgo = (flag) ? [self daysAgoAgainstMidnight] : [self daysAgo];
    NSString *text = nil;
    switch (daysAgo) {
    case 0:
        text = @"今天";
        break;
    case 1:
        text = @"昨天";
        break;
    case 2:
        text = @"前天";
        break;
    case -1:
        text = @"明天";
        break;
    case -2:
        text = @"后天";
        break;
    default:
        if (daysAgo > 0)
            text = [NSString stringWithFormat:@"%d天前", daysAgo];
        else
            text = [NSString stringWithFormat:@"%d天后", abs(daysAgo)];
    }
    return text;
}
//返回一周的第几天(周末为第一天)
- (NSUInteger)weekday {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *weekdayComponents = [calendar components:(NSCalendarUnitWeekday) fromDate:self];
    return [weekdayComponents weekday];
}

#pragma mark - 类方法
//转为NSString类型的
+ (NSDate *)dateFromString:(NSString *)string {
    return [NSDate dateFromString:string withFormat:[NSDate dbFormatString]];
}

+ (NSDate *)dateFromString:(NSString *)string withFormat:(NSString *)format {
    NSDateFormatter *inputFormatter = [[NSDateFormatter alloc] init];
    [inputFormatter setDateFormat:format];
    NSDate *date = [inputFormatter dateFromString:string];
    return date;
}

+ (NSString *)stringFromDate:(NSDate *)date withFormat:(NSString *)format {
    return [date stringWithFormat:format];
}

+ (NSString *)stringFromDate:(NSDate *)date {
    return [date string];
}

+ (NSString *)stringForDisplayFromDate:(NSDate *)date prefixed:(BOOL)prefixed {
    /*
     * if the date is in today, display 12-hour time with meridian,
     * if it is within the last 7 days, display weekday name (Friday)
     * if within the calendar year, display as Jan 23
     * else display as Nov 11, 2008
     */

    NSDate *today = [NSDate date];
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *offsetComponents = [calendar components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:today];

    NSDate *midnight = [calendar dateFromComponents:offsetComponents];

    NSDateFormatter *displayFormatter = [[NSDateFormatter alloc] init];
    NSString *displayString = nil;

    // comparing against midnight
    if ([date compare:midnight] == NSOrderedDescending) {
        if (prefixed) {
            [displayFormatter setDateFormat:@"'at' h:mm a"]; // at 11:30 am
        } else {
            [displayFormatter setDateFormat:@"h:mm a"]; // 11:30 am
        }
    } else {
        // check if date is within last 7 days
        NSDateComponents *componentsToSubtract = [[NSDateComponents alloc] init];
        [componentsToSubtract setDay:-7];
        NSDate *lastweek = [calendar dateByAddingComponents:componentsToSubtract toDate:today options:0];
        if ([date compare:lastweek] == NSOrderedDescending) {
            [displayFormatter setDateFormat:@"EEEE"]; // Tuesday
        } else {
            // check if same calendar year
            NSInteger thisYear = [offsetComponents year];

            NSDateComponents *dateComponents = [calendar components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:date];
            NSInteger thatYear = [dateComponents year];
            if (thatYear >= thisYear) {
                [displayFormatter setDateFormat:@"MMM d"];
            } else {
                [displayFormatter setDateFormat:@"MMM d, yyyy"];
            }
        }
        if (prefixed) {
            NSString *dateFormat = [displayFormatter dateFormat];
            NSString *prefix = @"'on' ";
            [displayFormatter setDateFormat:[prefix stringByAppendingString:dateFormat]];
        }
    }

    // use display formatter to return formatted date string
    displayString = [displayFormatter stringFromDate:date];
    return displayString;
}

+ (NSString *)stringForDisplayFromDate:(NSDate *)date {
    return [self stringForDisplayFromDate:date prefixed:NO];
}

- (NSString *)stringWithFormat:(NSString *)format {
    NSDateFormatter *outputFormatter = [[NSDateFormatter alloc] init];
    [outputFormatter setDateFormat:format];
    NSString *timestamp_str = [outputFormatter stringFromDate:self];
    return timestamp_str;
}

- (NSString *)string {
    return [self stringWithFormat:[NSDate dbFormatString]];
}

- (NSString *)stringWithDateStyle:(NSDateFormatterStyle)dateStyle timeStyle:(NSDateFormatterStyle)timeStyle {
    NSDateFormatter *outputFormatter = [[NSDateFormatter alloc] init];
    [outputFormatter setDateStyle:dateStyle];
    [outputFormatter setTimeStyle:timeStyle];
    NSString *outputString = [outputFormatter stringFromDate:self];
    return outputString;
}
//返回周日的的开始时间
- (NSDate *)beginningOfWeek {
    // largely borrowed from "Date and Time Programming Guide for Cocoa"
    // we'll use the default calendar and hope for the best

    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDate *beginningOfWeek = nil;
    BOOL ok = [calendar rangeOfUnit:NSCalendarUnitWeekdayOrdinal startDate:&beginningOfWeek interval:NULL forDate:self];
    if (ok) {
        return beginningOfWeek;
    }

    // couldn't calc via range, so try to grab Sunday, assuming gregorian style
    // Get the weekday component of the current date
    NSDateComponents *weekdayComponents = [calendar components:NSCalendarUnitWeekday fromDate:self];

    /*
     Create a date components to represent the number of days to subtract from the current date.
     The weekday value for Sunday in the Gregorian calendar is 1, so subtract 1 from the number of days to subtract from the date in question.  (If today's
     Sunday, subtract 0 days.)
     */
    NSDateComponents *componentsToSubtract = [[NSDateComponents alloc] init];
    [componentsToSubtract setDay:0 - ([weekdayComponents weekday] - 1)];
    beginningOfWeek = nil;
    beginningOfWeek = [calendar dateByAddingComponents:componentsToSubtract toDate:self options:0];

    // normalize to midnight, extract the year, month, and day components and create a new date from those components.
    NSDateComponents *components = [calendar components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:beginningOfWeek];
    return [calendar dateFromComponents:components];
}
//返回当前天的年月日.
- (NSDate *)beginningOfDay {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    // Get the weekday component of the current date
    NSDateComponents *components = [calendar components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:self];
    return [calendar dateFromComponents:components];
}
//返回该月的第一天
- (NSDate *)beginningOfMonth {
    return [self dateAfterDay:-[self getDay] + 1];
}
//该月的最后一天
- (NSDate *)endOfMonth {
    return [[[self beginningOfMonth] dateafterMonth:1] dateAfterDay:-1];
}
//返回当前周的周末
- (NSDate *)endOfWeek {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    // Get the weekday component of the current date
    NSDateComponents *weekdayComponents = [calendar components:NSCalendarUnitWeekday fromDate:self];
    NSDateComponents *componentsToAdd = [[NSDateComponents alloc] init];
    // to get the end of week for a particular date, add (7 - weekday) days
    [componentsToAdd setDay:(7 - [weekdayComponents weekday])];
    NSDate *endOfWeek = [calendar dateByAddingComponents:componentsToAdd toDate:self options:0];

    return endOfWeek;
}

+ (NSString *)dateFormatString {
    return @"yyyy-MM-dd";
}

+ (NSString *)timeFormatString {
    return @"HH:mm:ss";
}

+ (NSString *)timestampFormatString {
    return @"yyyy-MM-dd HH:mm:ss";
}

// preserving for compatibility
+ (NSString *)dbFormatString {
    return [NSDate timestampFormatString];
}
@end
